Various fuel injection control valves have been proposed; in one such known arrangement, a sleeve is frictionally retained in a passage guideway through which a magnetic core is guided. The magnetic coil is sealed from fluid by two O-rings, one of which is seated on the sleeve at the outside thereof adjacent the passage through the housing of the valve, and the other one is seated in a ring groove of the magnetic core. The outer O-ring is securely pressed against the housing of the valve and against the sleeve when the sleeve and valve are connected together. The other O-ring, that is the O-ring sealing the core, is seated at the inside of the sleeve, with biased compression. This arrangement is comparatively complex and does not ensure sealing of fluid with respect to the electrical portion of the valve, or its electric operating control, particularly over long operating periods. In due course, the seal may not be tight anymore.